Gaseous pathways in atelectatic ears.

Thirteen atelectatic ears were politzerized with CO2, O2, air, and N2. In consequence, the atelectasis in these ears disappeared, only to reappear again slowly. The reappearance of retraction corresponded in speed to the diffusion coefficient of the gases, indicating a regular diffusion process. At the same time, four of these politzerized patients were able to collapse the tympanic membrane of their air-filled middle ears abruptly through sniffing or swallowing. At least three patients could introduce air actively and voluntarily into their ears. These observations indicate that in atelectatic ears, as in normal ears, air can enter and leave the middle ear through one of two routes. One is the eustachian tube, through which air can pass both ways as a bolus. The second route is through the bloodstream, which gases enter and leave according to the rules of biologic diffusion. While the origin of negative pressure in atelectatic ears is unknown, this study shows that it may be a complex process stemming from a quantitative imbalance of loss versus gain of gas entry through either of the two routes.